.\" Copyright (c) 2003 Tim Kientzle <kientzle@acm.org>
.\" Copyright (c) 2003 Simon L. Nielsen <simon@FreeBSD.org>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd June 30, 2022
.Dt RESCUE 8
.Os
.Sh NAME
.Nm rescue
.Nd rescue utilities in
.Pa /rescue
.Sh DESCRIPTION
The
.Pa /rescue
directory contains a collection of common utilities intended for use
in recovering a badly damaged system.
With the transition to a dynamically-linked root beginning with
.Fx 5.2 ,
there is a real possibility that the standard tools in
.Pa /bin
and
.Pa /sbin
may become non-functional due to a failed upgrade or a disk error.
The tools in
.Pa /rescue
are statically linked and should therefore be more resistant to
damage.
However, being statically linked, the tools in
.Pa /rescue
are also less functional than the standard utilities.
In particular, they do not have full use of the locale,
.Xr pam 3 ,
and nsswitch libraries.
.Pp
If your system fails to boot, and it shows a prompt similar to:
.Pp
.Dl "Enter full pathname of shell or RETURN for /bin/sh: "
.Pp
the first thing to try running is the standard shell,
.Pa /bin/sh .
If that fails, try running
.Pa /rescue/sh ,
which is the
.Nm
shell.
To repair the system, the root partition must first be remounted
read-write.
This can be done with the following
.Xr mount 8
command:
.Pp
.Dl "/rescue/mount -uw /"
.Pp
The next step is to double-check the contents of
.Pa /bin , /sbin ,
and
.Pa /usr/lib ,
possibly mounting a
.Fx
rescue or
.Dq "live file system"
CD-ROM and copying files from there.
Once it is possible to successfully run
.Pa /bin/sh , /bin/ls ,
and other standard utilities, try rebooting back into the standard
system.
.Pp
The
.Pa /rescue
tools are compiled using
.Xr crunchgen 1 ,
which makes them considerably more compact than the standard
utilities.
To build a
.Fx
system where space is critical,
.Pa /rescue
can be used as a replacement for the standard
.Pa /bin
and
.Pa /sbin
directories; simply change
.Pa /bin
and
.Pa /sbin
to be symbolic links pointing to
.Pa /rescue .
Since
.Pa /rescue
is statically linked, it should also be possible to dispense with much
of
.Pa /usr/lib
in such an environment.
.Pp
In contrast to its predecessor
.Pa /stand ,
.Pa /rescue
is updated during normal
.Fx
source and binary upgrades.
.Sh FILES
.Bl -tag -width ".Pa /rescue" -compact
.It Pa /rescue
Root of the
.Nm
hierarchy.
.El
.Sh SEE ALSO
.Xr crunchgen 1 ,
.Xr crash 8
.Sh HISTORY
The
.Nm
utilities first appeared in
.Fx 5.2 .
.Sh AUTHORS
.An -nosplit
The
.Nm
system was written by
.An Tim Kientzle Aq Mt kientzle@FreeBSD.org ,
based on ideas taken from
.Nx .
This manual page was written by
.An Simon L. Nielsen Aq Mt simon@FreeBSD.org ,
based on text by
.An Tim Kientzle Aq Mt kientzle@FreeBSD.org .
.Sh BUGS
Most of the
.Nm
tools work even in a fairly crippled system.
The most egregious exception is the
.Nm
version of
.Xr vi 1 ,
which currently requires that
.Pa /usr
be mounted so that it can access the
.Xr termcap 5
files.
Hopefully, a failsafe
.Xr termcap 3
entry will eventually be added into the
.Xr ncurses 3
library, so that
.Pa /rescue/vi
can be used even in a system where
.Pa /usr
cannot immediately be mounted.
In the meantime, the
.Nm
version of the
.Xr ed 1
editor can be used from
.Pa /rescue/ed
if you need to edit files, but cannot mount
.Pa /usr .
